1. Field of the Invention
The present invention relates to an image forming apparatus in which an image bearing member bearing a toner image and an intermediate transfer member is brought into contact with and separated from each other.
2. Description of the Related Art
Conventionally, there has been an image forming apparatuses having a plurality of photosensitive members and an intermediate transfer belt, in which color photosensitive members (photosensitive members for yellow, magenta, and cyan) that are not used during monochrome printing are separated from the intermediate transfer belt during the monochrome printing (see, for example, Japanese Patent Application Laid-Open No. 2005-156776).
According to the invention described in Japanese Patent Application Laid-Open No. 2005-156776, a separation mechanism and a separation motor for separating the color photosensitive members from the intermediate transfer belt are provided. By separating the intermediate transfer belt from the color photosensitive members during monochrome printing, abrasion and damage to the intermediate transfer belt and the color photosensitive members may be reduced, and the service life of the image forming apparatus can be increased.
However, according to the invention described in Japanese Patent Application Laid-Open No. 2005-156776, when a sudden load to the separation motor occurs due to a catch of a gear for transmitting a drive force from the separation motor during the separation operation of the intermediate transfer belt, a separation operation failure may be caused. Further, in a case where a load to the separation motor has increased due to aging degradation, a separation operation failure may also be caused.
In this case, the color photosensitive members and the intermediate transfer belt may not be separated and always contact each other even during monochrome printing. Consequently, abrasion and damage to the intermediate transfer belt and the color photosensitive members occur more than necessary, which may decrease the service life of the image forming apparatus.